The present invention relates to a semiconductor device, and for example, a technique applicable to a semiconductor device having two circuits different in power voltage from each other.
A control circuit that generates a control signal of a power control element is integrated into one of the semiconductor devices. In the semiconductor device of this type, a voltage to be applied to the power control element, that is, a supply voltage of a power to be controlled is higher than a supply voltage of the control circuit. For that reason, in order to input the control signal to the power control element, a second control circuit may be disposed between the control circuit and the power control element. The supply voltage of the second control circuit is generally equal to or lower than the supply voltage of the power control element, and higher than the supply voltage of the control circuit. In the semiconductor device of this type, a circuit higher in the supply voltage needs to be separated from a circuit lower in the supply voltage.
As a separation structure that separates two circuits from each other, there are techniques disclosed in, for example, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2008-521256 and International Publication No. WO2012/157223.
For example, in the separation structure of Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2008-521256, an active region having a power IGBT (insulated gate bipolar transistor) is surrounded by a spiral field plate. The field plate disclosed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2008-521256 forms a closed loop on at least an outside end thereof.
Also, the separation structure disclosed in International Publication No. WO2012/157223 separates an anode region and a cathode region from each other. In this separation structure, a plurality of field plates separated from each other is arranged around the cathode region. The outermost peripheral field plate is coupled to the anode region, and the outermost peripheral field plate is coupled to the cathode region.